The present invention relates to a method for repairing substrate surfaces with an epoxy filler composition that does not require the application of a primer to the surface prior to application of the epoxy composition.
The use of epoxy compositions as fillers for automotive vehicle body repairs is well known. However, current commercial epoxy fillers typically require the use of an adhesion-promoting primer that is applied to the substrate prior to application of the filler. For example, U.S. Pat. Nos. 5,470,605 and 5,604,271 are directed to such a primer that includes a first composition comprising an epoxy compound dispersed in a first volatile organic solvent and a second composition comprising a mercaptan-terminated polymer and an amine-functional material dispersed in a second volatile organic solvent.
The use of thiol-cured epoxy compositions as adhesives or sealers is also known. U.S. Pat. No. 4,623,702 relates to a two part adhesive or sealing system that includes a first part comprising 29-52 weight percent of an amine curable epoxy resin and 48-71 weight percent of an isocyanate prepolymer and a second part comprising an amine hardener, a tertiary amine as a primary accelerator and a mercaptan terminated polymer as a secondary accelerator. Certain diamines are listed as possible amine hardeners. The amount of amine hardener is 0.3 to 16.7 weight percent, based on the total weight of the epoxy resin and isocyanate prepolymer. Japanese Published Patent Application (Kokai) No. 05-112632 relates to an adhesive composition that includes an epoxy resin, a polymercaptan curing agent, and a reaction initiator. Tertiary amines and polyamine derived from certain diamines are listed as possible reaction initiators. There is no example that includes both a tertiary amine and a diamine.
A need exists for an epoxy filler that does not require pre-application of a primer.